Magnetic leakage flux inspection head and magnetic leakage flux inspection device system

Abstract

To provide a leakage flux flaw detection head and a leakage flux flaw detection device system capable of reducing additional inspection working hours for a next process by reducing a dead zone in leakage flux flaw detection of a round rod up to approximately 0 to 20 mm.SOLUTION: A leakage flux flaw detection head 2 includes: a magnetizer 20 comprising a yoke 21 and an excitation coil 22; a sensor part 23 for detecting leakage flux leaked from a surface flaw of a round rod W magnetized by the magnetizer 20; a body 24 for supporting the magnetizer 20 and the sensor part 23; two pairs of left and right guide rollers 25 mounted to the body 24; and a balanced support mechanism that is mounted to the body 24 or the magnetizer 20 between the longitudinal directions of the two pairs of left and right guide rollers 25, and supports balancing of the body 24 while abutting on the surface of the round rod W when either pair of guide rollers 25 from among the two pairs of left and right guide rollers 25 exceeds the edge of the round rod W.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a leakage flux inspection head and a leakage flux inspection device system, and in particular to a leakage flux inspection head and a leakage flux inspection device system for inspecting surface defects in steel bars having a round cross section or tubular steel pipes. [Background technology]

[0002] Steel bars and steel pipes that have been subjected to plastic deformation such as rolling may have various surface defects on their surfaces, and if these defects are sent to the next process, problems will arise with the quality of the product. Therefore, before being sent to the next process, the surfaces of the above steel bars and steel pipes are inspected for defects, and any surface defects detected are removed by grinding with a grinder or the like, thereby ensuring the yield and quality of the product.

[0003] Magnetic leakage flux testing is known as an inspection method for detecting surface defects in steel bars and steel pipes. Magnetic leakage flux testing is a method in which, when a magnetic material to be inspected is magnetized by applying a magnetic field, if there is a surface defect on the surface of the material that blocks the magnetic flux, the magnetic flux leaks from the surface, and the leakage magnetic flux is detected by a sensor to detect surface defects.

[0004] 4 is a diagram showing a schematic configuration of a conventional leakage magnetic flux inspection system. The conventional leakage magnetic flux inspection system 51 includes a rotating roller mechanism 3 that rotates a round bar W in a circumferential direction, a leakage magnetic flux inspection head 52 that inspects surface defects of the round bar W, an inspection head operation mechanism 4 that raises and lowers the leakage magnetic flux inspection head 52 and causes the inspection head traveling device 42 to travel on a traveling line 44 to advance the leakage magnetic flux inspection head 52 in the longitudinal direction on the surface of the round bar W, and an inspection operation control device 55 that controls the inspection operation.

[0005] The inspection operation is performed as follows: When the round bar W is placed on the rotating roller mechanism 3, the leakage flux inspection head 52 is lowered from a standby position onto the round bar W on the rotating rollers 35 by the inspection head lifting device 40. When the leakage flux inspection head 52 moves to the end of the round bar W by the inspection head traveling device 42, the rotating roller mechanism 3 rotates the round bar W in the circumferential direction, and the inspection head traveling device 42 advances the leakage flux inspection head 52 in the longitudinal direction of the round bar W to inspect the surface of the round bar W in a spiral shape, and a marking gun or the like (not shown) is activated to spray paint or the like on any part determined to be a surface defect. When the leakage magnetic flux inspection head 52 reaches the opposite end of the round bar W, inspection is terminated, the rotation of the round bar W stops, and the leakage magnetic flux inspection head 52 is lifted from the round bar W by the inspection head lifting device 40, and then travels in the opposite direction, to the left, by the inspection head traveling device 42 and returns to the original waiting position.

[0006] FIG. 5 shows an explanatory diagram of a conventional leakage flux inspection head at the end of a round bar. FIG. 5(a) is a front view, FIG. 5(b) is a left side view, and FIG. 5(c) is a cross-sectional view taken along the line AA in FIG. 5(a). The leakage flux inspection head 52 is composed of a magnetizer 20 consisting of an inverted U-shaped yoke 21 and an excitation coil 22, a sensor unit 23 that detects leakage flux leaking from surface defects of the round bar W magnetized by the magnetizer 20, a main body 24 that supports the magnetizer 20 and the sensor unit 23, and two pairs of guide rollers 25 attached to the main body 24. The guide rollers 25 contact the surface of the round bar W and rotate in the opposite direction to the rotation direction of the round bar W, and can also rotate in the vertical direction of the mounting axis of the guide rollers 25, so that the contact resistance is small and the movement of the main body 24 in the longitudinal direction of the round bar W by the inspection head traveling device 42 can be performed smoothly. The position sensor 26 detects the end of the round bar W, and is useful for controlling the position of the guide roller 25 and the sensor unit 23, that is, the distance from the end of the round bar W. The sensor unit 23 is configured by arranging multiple differential coils between both magnetic poles of the yoke 21 in the longitudinal direction.

[0007] In order to ensure uniformity of the magnetic flux of the sensor unit 23, the length S of the sensor unit 23 is about 1 / 2 to 2 / 3 of the length of the yoke 21. If the length between the outer sides of the guide rollers 25 is L, when one side of the guide rollers 25 starts flaw detection from the end of the round bar W, the position where the sensor unit 23 can start flaw detection is a position (LS) / 2 from the end of the round bar W, and the area from the end of the round bar W to this position is a dead zone where leakage magnetic flux flaw detection is not possible. The same is true for the end position on the opposite side of the round bar W where the sensor unit 23 ends flaw detection, which is a position (LS) / 2 from the end of the opposite side of the round bar W, and the area from the end of the opposite side of the round bar W to this position is a dead zone where leakage magnetic flux flaw detection is not possible.

[0008] The dead zones at both ends of the round bar W, where the above-mentioned leakage magnetic flux inspection is not possible, are approximately 150 mm to 300 mm, depending on the size of the round bar W. In order to guarantee the dead zones at both ends, additional labor was required, such as visual inspection of the dead zones or inspection of the dead zones using a dedicated inspection device for dead zones (Patent Document 1). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2001-330592 A Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made to solve the problems of the conventional technology described above, and has an object to provide a leakage flux inspection head and leakage flux inspection device system that can shorten the dead zone in leakage flux inspection of round bars to approximately 0 mm to 20 mm, thereby reducing additional inspection labor for the next process. [Means for solving the problem]

[0011] In order to solve the above problems, the present inventors conducted extensive research and obtained the following findings. (1) In conventional magnetic leakage flux inspection heads, when one of a pair of guide rollers passes the end of a round bar, the head tilts, changing the lift-off in the longitudinal direction of the sensor part, making inspection difficult. Furthermore, the magnetic pole of the yoke or the sensor part close to the surface of the round bar comes into contact with the bar and is damaged. For this reason, the guide rollers could only move up to the end of the round bar. (2) If a function is added to support balance so that the leakage flux inspection head does not tilt when one of the pairs of guide rollers passes the end of the round bar, by contacting the surface of the round bar between the longitudinal direction of the two pairs of guide rollers before the magnetic pole of the yoke or the sensor part, the lift-off in the longitudinal direction of the sensor part will not change, and the magnetic pole of the yoke or the sensor part close to the surface of the round bar will not come into contact with the round bar and be damaged. This will also expand the inspection range and shorten the dead zone. (3) When one of the pair of guide rollers passes the end of the round bar, the head will come into contact with the surface of the round bar before the magnetic pole of the yoke or the sensor part, and in order to maintain balance so that the leakage flux inspection head does not tilt, we considered a method of supporting it with a sliding part such as a shoe or a method of supporting it with a rotating part such as a roller.However, since the head comes into contact with the rotating round bar, the method of supporting it with a rotating part such as a roller, which has smaller contact resistance, is preferable. (4) When two pairs of guide rollers are located in the inner region of the end of the round bar, the function of supporting balance by contacting the rotating round bar is not necessary, and it is preferable to have a release function when the function of supporting balance is maintained.

[0012] Based on the above findings, the leakage flux inspection head of the present invention is a leakage flux inspection head that advances in the longitudinal direction on the surface of a round bar rotating in the circumferential direction to inspect surface defects of the round bar by a leakage flux inspection method, and includes a magnetizer consisting of a yoke and an excitation coil, a sensor unit that detects leakage flux leaking from surface defects of the round bar magnetized by the magnetizer, a main body that supports the magnetizer and the sensor unit, two pairs of left and right guide rollers attached to the main body, and between the longitudinal directions of the two pairs of left and right guide rollers: A rod-shaped roller whose longitudinal length is longer than the length of the sensor unit and shorter than the distance between the two pairs of left and right guide rollers. The main body or the magnetizer The balance support is not in contact with the surface of the round bar.When one of the two pairs of guide rollers on the left and right passes the end of the round bar, The rod-shaped roller and a balance support mechanism that contacts the surface of the round bar to support the balance of the main body.

[0013] The leakage flux inspection head of the present invention is a leakage flux inspection head that advances in the longitudinal direction on the surface of a round bar rotating in the circumferential direction to inspect the surface defects of the round bar by the leakage flux inspection method, and includes a magnetizer consisting of a yoke and an excitation coil, a sensor unit that detects leakage flux leaking from surface defects of the round bar magnetized by the magnetizer, a main body that supports the magnetizer and the sensor unit, two pairs of left and right guide rollers attached to the main body, and between the longitudinal directions of the two pairs of left and right guide rollers, A metal plate with ball rollers, the length of which in the longitudinal direction is longer than the length of the sensor unit and shorter than the distance between the two pairs of left and right guide rollers, The main body or the magnetizer The balance support is not in contact with the surface of the round bar. When one of the two pairs of guide rollers on the left and right passes the end of the round bar, The metal plate with ball rollers and a balance support mechanism that contacts the surface of the round bar to support the balance of the main body.

[0014] According to the present invention, between the two pairs of left and right guide rollers in the longitudinal direction, The longitudinal length is longer than the length of the sensor section and shorter than the distance between the two pairs of guide rollers on the left and right. The metal plate is equipped with rod-shaped rollers or ball rollers. Main body or magnetizer With the balance support part of the rod not touching the surface A balance support mechanism is provided that, when one of the two pairs of guide rollers on the left and right sides passes the end of the round bar, it comes into contact with the surface of the round bar to support the balance of the main body.This means that the leakage flux inspection head does not tilt, the lift-off in the longitudinal direction of the sensor unit does not change, and the magnetic poles of the yoke or the sensor unit close to the surface of the round bar do not come into contact with the round bar and are damaged.This also means that the inspection range can be expanded and the dead zone at the end of the round bar can be shortened.

[0015] Furthermore, the leakage flux inspection head of the present invention is a leakage flux inspection head that advances in the longitudinal direction on the surface of a round bar rotating in the circumferential direction to inspect surface defects of the round bar by a leakage flux inspection method, and includes a magnetizer consisting of a yoke and an excitation coil, a sensor unit that detects leakage flux leaking from surface defects of the round bar magnetized by the magnetizer, a main body that supports the magnetizer and the sensor unit, two pairs of left and right guide rollers attached to the main body, and between the longitudinal directions of the two pairs of left and right guide rollers, A rod-shaped roller whose longitudinal length is longer than the length of the sensor unit and shorter than the distance between the two pairs of left and right guide rollers is rotatable. The main body or the magnetizer The balance support is not in contact with the surface of the round bar. In the region where one of the two pairs of guide rollers on the left and right side of the round bar extends beyond the end of the round bar from a predetermined position on the end of the round bar, The rod-shaped roller The present invention is characterized in that it is equipped with a balance support mechanism that contacts the surface of the round bar to activate the balance support mechanism that supports the balance of the main body, and a release mechanism that releases the balance support mechanism in the area between the two pairs of left and right guide rollers at predetermined positions on the end of the round bar.

[0016] The leakage flux inspection head of the present invention is a leakage flux inspection head that advances in the longitudinal direction on the surface of a round bar rotating in the circumferential direction to inspect the surface defects of the round bar by the leakage flux inspection method, and includes a magnetizer consisting of a yoke and an excitation coil, a sensor unit that detects leakage flux leaking from surface defects of the round bar magnetized by the magnetizer, a main body that supports the magnetizer and the sensor unit, two pairs of left and right guide rollers attached to the main body, and between the longitudinal directions of the two pairs of left and right guide rollers, A metal plate with ball rollers, the length of which in the longitudinal direction is longer than the length of the sensor unit and shorter than the distance between the two pairs of left and right guide rollers, is rotatable. The main body or the magnetizer The balance support is not in contact with the surface of the round bar. In the region where one of the two pairs of guide rollers on the left and right side of the round bar extends beyond the end of the round bar from a predetermined position on the end of the round bar, The metal plate with ball rollers The present invention is characterized in that it is equipped with a balance support mechanism that contacts the surface of the round bar to activate the balance support mechanism that supports the balance of the main body, and a release mechanism that releases the balance support mechanism in the area between the two pairs of left and right guide rollers at predetermined positions on the end of the round bar.

[0017] According to the present invention, between the two pairs of left and right guide rollers in the longitudinal direction, The longitudinal length is longer than the length of the sensor section and shorter than the distance between the two pairs of guide rollers on the left and right. A metal plate with rod-shaped rollers or ball rollers can rotate. Main body or magnetizer With the balance support part of the rod not touching the surfaceThe head is equipped with two pairs of guide rollers, one on the left and one on the right, which come into contact with the surface of the round bar in the area where it moves from a predetermined position at the end of the round bar to beyond the end, activating a balance support mechanism that supports the balance of the main body, and a release mechanism that releases the balance support mechanism in the area between the two pairs of guide rollers, which move from the predetermined position at the end of the round bar to beyond the end, so that in the area where either pair of guide rollers comes into contact with the surface of the round bar and the balance support mechanism that supports the balance of the main body is activated, the leakage magnetic flux inspection head does not tilt, the lift-off in the longitudinal direction of the sensor unit does not change, and the magnetic poles of the yoke or the sensor unit close to the surface of the round bar do not come into contact with the round bar and are damaged, and as a result, the inspection range is expanded and the dead zone at the end of the round bar is shortened. Furthermore, in the area between the two pairs of guide rollers on the left and right, which are at the specified positions on the end of the round bar, a release mechanism is activated to release the balance support mechanism, releasing contact with the surface of the round bar, so that only the two pairs of guide rollers on the left and right are in contact with the surface of the round bar, allowing the leakage flux inspection head to move smoothly in the longitudinal direction.

[0018] Preferably, in the leakage flux inspection head, the balance support mechanism is made of a rotating member.

[0019] The balance support mechanism that maintains the balance of the main body so that the leakage flux inspection head does not tilt is in contact with the rotating round bar, so it is preferable that it be made of a rotating member such as a roller that has a smaller contact resistance.

[0020] In addition, preferably, the leakage flux inspection head is characterized in that the longitudinal length of the balance support mechanism is longer than the length of the sensor unit and shorter than the length between the two pairs of left and right guide rollers.

[0021] If the longitudinal length of the balance support mechanism is longer than the length of the sensor section, the dead zone at the end of the round bar can be shortened; however, if it is longer than the length between the two pairs of guide rollers on the left and right, the weight will increase and it will be difficult to install mechanically, so it is preferable that it is shorter than the length between the two pairs of guide rollers on the left and right.

[0022] In addition, the leakage flux inspection equipment system of the present invention is characterized in that it comprises a rotating roller mechanism that rotates a round bar in a circumferential direction, a leakage flux inspection head that inspects surface defects of the round bar, an inspection head operating mechanism that raises and lowers the leakage flux inspection head and moves it longitudinally over the surface of the round bar, and an inspection operation control device that controls the inspection operation, and is equipped with any of the leakage flux inspection heads described above.

[0023] According to the present invention, a conventional leakage flux inspection device system has been reconstructed by applying a leakage flux inspection head that can shorten the dead zone portion at the end of a round bar. Therefore, the leakage flux inspection device system of the present invention can provide a leakage flux inspection device system that can reduce labor costs, such as performing additional visual inspection of the dead zone portion for the next process, or additional inspection of the dead zone portion using a detector dedicated to dead zone portions. Effect of the Invention

[0024] According to the leakage flux inspection head of the present invention, even if one of the two pairs of guide rollers on the left and right goes beyond the end of the round bar, the head is provided with a balance support mechanism that contacts the surface of the round bar to support the balance of the main body, so the leakage flux inspection head does not tilt, the lift-off in the longitudinal direction of the sensor does not change, and the magnetic pole of the yoke or the sensor part close to the surface of the round bar is not damaged by contacting the round bar, and this widens the inspection range and shortens the dead zone of the end of the round bar. In addition, the leakage flux inspection device system to which the leakage flux inspection head of the present invention is applied can reduce the man-hours required for additional visual inspection of the dead zone for the next process, or additional inspection of the dead zone with a dedicated inspection device for the dead zone. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is an explanatory diagram of a pair of guide rollers of a leakage flux inspection head according to a first embodiment of the present invention when they pass over the end of a round bar, where FIG. 1(a) is a front view, FIG. 1(b) is a left side view, and FIG. 1(c) is a cross-sectional view taken along line AA in FIG. 1(a). [Diagram 2]Figure 2 is an explanatory diagram of a leakage flux inspection head according to a second embodiment of the present invention at the end of a round bar, where Figure 2(a) is a front view of the leakage flux inspection head at a predetermined position on the round bar, Figure 2(b) is a front view of a pair of guide rollers of the leakage flux inspection head at a position beyond the end of the round bar, Figure 2(c) is a cross-sectional view taken along line AA in Figure 2(a), and Figure 2(d) is a cross-sectional view taken along line AA in Figure 2(b). [Diagram 3] Figure 3 shows an example of inspection operation control when using a leakage flux inspection head of the present invention, where Figure 3(a) corresponds to the inspection operation control of the leakage flux inspection head of the first embodiment, and Figure 3(b) corresponds to the inspection operation control of the leakage flux inspection head of the second embodiment. [Figure 4] FIG. 4 is a diagram showing a schematic configuration of a conventional magnetic leakage flux flaw detector system. [Diagram 5] FIG. 5 is an explanatory diagram of a conventional leakage flux inspection head at the end of a round bar, where FIG. 5(a) is a front view, FIG. 5(b) is a left side view, and FIG. 5(c) is a cross-sectional view taken along line AA in FIG. 5(a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the present invention, the term "round bar" is not limited to a solid bar-shaped body, but also includes a hollow tubular body.

[0027] <First embodiment> FIG. 1 is an explanatory diagram of a pair of guide rollers of a leakage flux inspection head according to a first embodiment of the present invention when they pass over the end of a round bar, where FIG. 1(a) is a front view, FIG. 1(b) is a left side view, and FIG. 1(c) is a cross-sectional view taken along line AA in FIG. 1(a).

[0028] The leakage flux inspection head 2 of this embodiment includes a magnetizer 20 consisting of an inverted U-shaped yoke 21 and an excitation coil 22, a sensor unit 23 that detects leakage flux leaking from surface defects in the round bar W magnetized by the magnetizer 20, a main body 24 that supports the magnetizer 20 and the sensor unit 23, two pairs of left and right guide rollers 25 attached to the main body 24, and a rod-shaped roller 28 and a balance support unit 27 supporting it are attached to the main body 24 between the longitudinal directions of the two pairs of left and right guide rollers 25 as a balance support mechanism that supports the balance of the main body 24.

[0029] When the two pairs of guide rollers 25 on the left and right are in contact with the surface of the round bar W, the surfaces of the rod-shaped rollers 28 are set to be spaced apart from the surface of the round bar W by about 0.5 mm so as not to directly contact the round bar W. When one of the two pairs of guide rollers 25 on the left and right passes over the end of the round bar W, the surfaces of the rod-shaped rollers 28 come into contact with the surface of the round bar W, and can support the balance of the main body 24 so that the leakage flux flaw detection head 2 does not tilt. Figures 1(a) and 1(b) show a front view and a left side view when the left pair of guide rollers 25 passes over the end of the round bar W and the left side of the sensor unit 23 reaches the end of the round bar W. In Fig. 1(c), which shows a cross section taken along line AA in Fig. 1(a), rod-shaped rollers 28 and the balancing support part 27 that supports them act as a balancing support mechanism, making it possible to perform leakage flux inspection even if one of the two pairs of guide rollers 25 on the left and right goes beyond the end of the round bar W. As a result, the dead zone that occurs at the end of the round bar W, which was a problem with conventional leakage flux inspection heads, has been reduced to almost zero.

[0030] Also, rod-shaped of If the longitudinal length of roller 28 is longer than the length of sensor section 23, the balance of main body 24 will be stabilized and the dead zone at the end of round bar W can be shortened. However, if the longitudinal length of roller 28 is longer than the length between two pairs of guide rollers 25 on the left and right, the weight will increase and it will be difficult to install mechanically. Therefore, it is preferable that the longitudinal length of roller 28 is shorter than the length between two pairs of guide rollers 25 on the left and right.

[0031] In this embodiment, rod-shaped rollers 28 and the balancing support part 27 that supports them are used as the rotating members of the balancing support mechanism, but instead of the rod-shaped rollers 28, a plate-shaped rotating member with ball rollers embedded in the longitudinal direction may be attached to the balancing support part 27 and function in the same manner as the rod-shaped rollers 28. In this case, too, the gap between the surface of the ball rollers and the surface of the round bar W is set to about 0.5 mm. Also, although the balancing support part 27 is attached to the main body 24, it may be attached to the magnetizer 20. The members of the above-mentioned balancing support mechanism are preferably made of non-magnetic stainless steel or the like.

[0032] Furthermore, the inspection operation control device 5 controls the inspection head travel device 42 so that the distance from the point where the position sensor 26 of the leakage flux inspection head 2 detects that the guide roller 25 has moved beyond the end of the round bar W is a distance that takes into consideration the position of the center of gravity of the leakage flux inspection head 2 and safety. Therefore, depending on the relationship between the distance between the left and right guide rollers 25 and the length of the sensor unit 23, it may not be possible to reduce the dead zone to zero, but since the dead zone can be shortened to around 20 mm, additional inspection man-hours for the dead zone are not required for the next process.

[0033] <Second embodiment> Figure 2 is an explanatory diagram of a leakage flux inspection head according to a second embodiment of the present invention at the end of a round bar, where Figure 2(a) is a front view of the leakage flux inspection head at a predetermined position on the round bar, Figure 2(b) is a front view of a pair of guide rollers of the leakage flux inspection head at a position beyond the end of the round bar, Figure 2(c) is a cross-sectional view taken along line AA in Figure 2(a), and Figure 2(d) is a cross-sectional view taken along line AA in Figure 2(b).

[0034] The leakage magnetic flux inspection head 2 of this embodiment is equipped with a magnetizer 20 consisting of an inverted U-shaped yoke 21 and an excitation coil 22, a sensor unit 23 that detects leakage magnetic flux leaking from surface defects of the round bar W magnetized by the magnetizer 20, a main body 24 that supports the magnetizer 20 and the sensor unit 23, two pairs of left and right guide rollers 25 attached to the main body 24, and a balance support mechanism that comes into contact with the surface of the round bar W and supports the balance of the main body 24, and is composed of a metal plate with ball rollers 29 in which ball rollers are embedded in the longitudinal direction as rotating members of the balance support mechanism and a balance support unit 27, and a release mechanism that releases the balance support mechanism that comes into contact with the surface of the round bar W, which are attached to the magnetizer 20.

[0035] In the region where one of the two pairs of guide rollers 25 on the left and right sides moves from a predetermined position at the end of the round bar W to beyond the end, it contacts the surface of the round bar W to activate a balance support mechanism that supports the balance of the main body 24, and in the region between the two pairs of guide rollers 25 on the left and right sides and the predetermined positions at the end of the round bar W, a release mechanism is provided which releases the balance support mechanism.

[0036] First, in the region (see FIG. 2(b)) where one of the two pairs of guide rollers 25 on the left and right goes beyond a predetermined position on the end of the round bar W (for example, the position where the position sensor 26 on the left side of FIG. 2(a) detects the end of the round bar W), the metal plate 29 with ball rollers is rotated at the predetermined position from the horizontal position of the balancing support part 27 (see FIG. 2(c)) to a position where the ball rollers contact the surface of the round bar W, thereby activating the balancing support mechanism that supports the balance of the main body 24 (see FIG. 2(d)). As a result, even if the pair of guide rollers 25 passes over the end of the round bar W, the ball rollers of the metal plate 29 with ball rollers come into contact with the surface of the round bar W and support the balance of the main body 24, so that the leakage flux flaw detection head 2 does not tilt, the lift-off in the longitudinal direction of the sensor part 23 does not change, and the magnetic poles of the yoke 21 or the sensor part 23 close to the surface of the round bar W are not damaged by contacting the round bar W, and this also widens the flaw detection range and shortens the dead zone of the end of the round bar W. Furthermore, the ball rollers of the metal plate 29 with ball rollers have a degree of freedom to follow not only the rotational direction of the round bar W but also the rotational direction of the movement in the longitudinal direction, which is advantageous in reducing contact resistance.

[0037] 2(a) and 2(c) will be used to explain that the balancing support mechanism is released in the region between the two pairs of left and right guide rollers 25 at the predetermined positions of the end of the round bar W. In the region between the predetermined positions (for example, between the position where the left position sensor 26 detects the left end of the round bar W and the position where the right position sensor 26 detects the right end of the round bar W), it is sufficient to proceed with the highly accurate guide rollers 25, and the metal plate 29 with ball rollers is rotated in the reverse direction from the position where the ball rollers contact the surface of the round bar W at the predetermined position to the horizontal position of the balancing support part 27, thereby releasing the balancing support mechanism.

[0038] The actuation and release of the balancing support mechanism by the rotation and reverse rotation of the balancing support part 27 of the metal plate with ball rollers 29 from the horizontal position can be achieved in various ways, for example, by directly driving the rotation shaft of the metal plate with ball rollers 29 with a geared motor attached to the balancing support part 27, or by indirectly rotating the metal plate with ball rollers 29 about its axis by pressing up and down the part of the metal plate with ball rollers 29 away from the rotation shaft with a motorized latch gear or flat gear attached to the balancing support part 27.

[0039] <Third embodiment> The third embodiment is a leakage flux inspection system to which the leakage flux inspection head of the present invention is applied. In the leakage flux inspection system of the present invention, one pair of guide rollers of the leakage flux inspection head exceeds the end of the round bar, so that the inspection operation control is different from the conventional one. Therefore, in the schematic configuration of the conventional leakage flux inspection system shown in FIG. 4, if the conventional leakage flux inspection head 52 is replaced with the leakage flux inspection head 2 of the present invention and the conventional inspection operation control device 55 is replaced with the inspection operation control device 5 of the present invention, the leakage flux inspection system of the present invention is obtained. The leakage flux inspection system 1 of this embodiment is a leakage flux inspection system 1 including a rotating roller mechanism 3 that rotates the round bar W in the circumferential direction, a leakage flux inspection head 2 of the present invention that inspects surface defects of the round bar W, a flaw detection head operation mechanism 4 that raises and lowers the leakage flux inspection head 2 and advances it in the longitudinal direction on the surface of the round bar W, and a flaw detection operation control device 5 that controls the inspection operation.

[0040] 3(a) is an example showing the inspection operation control when the leakage flux inspection head of the first embodiment is used. The solid arrow indicates the movement of the guide roller 25 on the left side of the leakage flux inspection head 2, and the dashed arrow indicates the movement of the guide roller 25 on the right side of the leakage flux inspection head 2. Note that for the sake of illustration in the drawings, steps S2 and S3 are at different heights, but steps S2 and S3 are at the same height where they contact the surface of the round bar W. The inspection operation control is performed as follows. When the round bar W is placed on the rotating roller 35 and starts to rotate, the leakage flux inspection head 2 is lowered from the standby position to the round bar W on the rotating roller 35 by the inspection head lifting device 40 (step S1). The leakage flux inspection head 2 starts moving leftward by the inspection head travel device 42, and when the left guide roller 25 passes the left end of the round bar W, the surface of the rod-shaped roller 28 comes into contact with the surface of the round bar W, supporting the balance of the main body 24, and moves to a position where safety is considered (step S2). Inspection starts from that position, and the inspection head travel device 42 advances the leakage flux inspection head 2 to the right in the longitudinal direction of the round bar W to inspect the surface of the round bar W in a spiral shape, and when the guide roller 25 on the right side of the leakage flux inspection head 2 passes the right end of the round bar W, the surface of the rod-shaped roller 28 comes into contact with the surface of the round bar W again, supporting the balance of the main body 24, and moves to a position where safety is considered, and inspection ends (step S3). In step S3, when the two pairs of guide rollers 25 are between both ends of the round bar W, the surfaces of the rod-shaped rollers 28 are set to be spaced apart from the surface of the round bar W by about 0.5 mm, and therefore do not come into contact with the surface of the round bar W. When the flaw detection is completed, the leakage flux flaw detection head 2 is lifted up from the round bar W by the flaw detection head lifting device 40 (step S4). The flaw detection head traveling device 42 travels in the opposite direction, to the left, and the leakage flux flaw detection head 2 returns to its original standby position (step S5). Thereafter, the rotation of the rotating rollers 35 is stopped, and the rotation of the round bar W is stopped.

[0041] 3(b) is an example showing the inspection operation control when the leakage flux inspection head of the second embodiment is used. The solid arrow indicates the movement of the guide roller 25 on the left side of the leakage flux inspection head 2, and the dashed arrow indicates the movement of the guide roller 25 on the right side of the leakage flux inspection head 2. For the sake of illustration, steps T2 and T3 and steps T4, T5, and T6 are at different heights, but these steps are at the same height where they contact the surface of the round bar W. The inspection operation is performed as follows. When the round bar W is placed on the rotating roller 35 and starts to rotate, the leakage flux inspection head 2 is lowered from the standby position to the round bar W on the rotating roller 35 by the inspection head lifting device 40 (step T1). The leakage flux inspection head 2 starts moving leftward by the inspection head travel device 42, and when the left guide roller 25 reaches a predetermined position from the end of the round bar W, the metal plate 29 with ball rollers is rotated from the horizontal position of the balance support part 27 to a position where the ball rollers contact the surface of the round bar W, and the balance support mechanism that supports the balance of the main body 24 is activated (step T2). Furthermore, even if the left guide roller 25 passes the end of the round bar W, it supports the balance of the main body 24 and moves to a position where safety is taken into consideration (step T3). Flaw detection is started from that position, and the inspection head travel device 42 advances the leakage flux inspection head 2 to the right in the longitudinal direction of the round bar W to spirally inspect the surface of the round bar W, and when the left guide roller 25 of the leakage flux inspection head 2 reaches a predetermined position from the end of the round bar W, the metal plate 29 with ball rollers is rotated in the opposite direction from the position where the ball rollers contact the surface of the round bar W, and the balance support mechanism that supports the balance of the main body 24 is released (step T4). With the balance support mechanism released, the spiral inspection continues on the surface of the round bar W, and this time when the right guide roller 25 reaches a predetermined position from the end of the round bar W, the balance support mechanism is activated again (step T5). Furthermore, even if the right guide roller 25 passes the end of the round bar W, it supports the balance of the main body 24, and when it moves to a position where safety is taken into consideration, inspection ends (step T6). When inspection ends, the leakage flux inspection head 2 is lifted up from the round bar W by the inspection head lifting device 40, and then the balance support mechanism is released (step T7). The inspection head traveling device 42 travels in the opposite direction, to the left, and the leakage flux inspection head 2 returns to its original standby position (step T8).Thereafter, the rotation of the rotary roller 35 is stopped, and the rotation of the round bar W is also stopped.

[0042] In either type of flaw detection operation control, the surface of the round bar W is inspected in a spiral shape, and a marking gun (not shown) is operated to spray paint or the like on the parts that are detected as surface flaws. The marked surface flaws are removed by grinding with a grinder or the like before being sent to the next process, thereby ensuring the product yield and quality.

[0043] In the above embodiment of the leakage flux inspection device system 1, a single leakage flux inspection head 2 is used, but two leakage flux inspection heads 2 may be used, with one head simultaneously inspecting from the left end to the center of the round bar W and the other head simultaneously inspecting from the center to the right end of the round bar W.

[0044] The leakage flux inspection head and leakage flux inspection device system of the present invention have been described above based on examples. However, the present invention is not limited to the structure and inspection operation control described in the above examples, and the structure and inspection operation control can be changed as appropriate within the scope of the invention. [Explanation of symbols]

[0045] 1. Magnetic leakage flux inspection system 2. Magnetic leakage flux inspection head 3 Rotating roller mechanism 4. Inspection head operation mechanism 5. Flaw detection operation control device 20 Magnetizer 21 York 22 Excitation coil 23 Sensor section 24 Main Unit 25 Guide roller 26 Position Sensor 27 Balance support part 28 Rod-shaped roller 29 Metal plate with ball rollers 35 Rotating Roller 40 Flaw detection head lifting device 42 Flaw detection head travel device 44 Driving Line 51 Conventional magnetic leakage flux inspection system 52 Conventional leakage flux inspection head 55 Conventional flaw detection operation control device W round bar

Claims

1. a magnetizer consisting of a yoke and an excitation coil; a sensor unit that detects leakage magnetic flux leaking from surface defects of the round bar magnetized by the magnetizer; a main body that supports the magnetizer and the sensor unit; two pairs of left and right guide rollers attached to the main body; and a rod-shaped roller that is attached to the balance support unit of the main body or the magnetizer between the longitudinal direction of the two pairs of left and right guide rollers and has a longitudinal length longer than the length of the sensor unit and shorter than the length between the two pairs of left and right guide rollers, the rod-shaped roller being attached to the balance support unit of the main body or the magnetizer without contacting the surface of the round bar, and when one of the two pairs of left and right guide rollers passes the end of the round bar, the rod-shaped roller comes into contact with the surface of the round bar, thereby supporting the balance of the main body.

2. a magnetizer consisting of a yoke and an excitation coil; a sensor unit that detects leakage flux leaking from surface defects of the round bar magnetized by the magnetizer; a main body that supports the magnetizer and the sensor unit; two pairs of left and right guide rollers attached to the main body; and a balance support mechanism that supports the balance of the main body and has a longitudinal length longer than the length of the sensor unit and shorter than the length between the two pairs of left and right guide rollers, the balance support mechanism being attached to the main body or the balance support part of the magnetizer between the longitudinal directions of the two pairs of left and right guide rollers without contacting the surface of the round bar, and when one of the two pairs of left and right guide rollers passes the end of the round bar, the metal plate with ball rollers comes into contact with the surface of the round bar, thereby supporting the balance of the main body.

3. A leakage flux inspection head for detecting surface defects of a round bar by a leakage flux inspection method by moving in a longitudinal direction on the surface of the round bar rotating in a circumferential direction, the head comprising: a magnetizer consisting of a yoke and an exciting coil; a sensor unit for detecting leakage flux leaking from surface defects of the round bar magnetized by the magnetizer; a main body for supporting the magnetizer and the sensor unit; two pairs of left and right guide rollers attached to the main body; and a bar having a longitudinal length between the two pairs of left and right guide rollers, the longitudinal length being longer than the length of the sensor unit and shorter than the length between the two pairs of left and right guide rollers. a rod-shaped roller is rotatably attached to the balance support part of the main body or the magnetizer without contacting the surface of the round bar, and in a region where one of the two pairs of left and right guide rollers moves from a predetermined position on the end of the round bar to beyond the end, the rod-shaped roller contacts the surface of the round bar to activate a balance support mechanism that supports the balance of the main body, and a release mechanism is provided for releasing the balance support mechanism in a region between the two pairs of left and right guide rollers and the predetermined positions on the end of the round bar.

4. A leakage flux inspection head that advances in a longitudinal direction on the surface of a round bar rotating in a circumferential direction to inspect the surface defects of the round bar by a leakage flux inspection method, the head comprising: a magnetizer consisting of a yoke and an excitation coil; a sensor unit that detects leakage flux leaking from surface defects of the round bar magnetized by the magnetizer; a main body that supports the magnetizer and the sensor unit; two pairs of left and right guide rollers attached to the main body; and a ball roller that is disposed between the longitudinal direction of the two pairs of left and right guide rollers and has a longitudinal length longer than the length of the sensor unit and shorter than the length between the two pairs of left and right guide rollers. a metal plate with ball rollers is rotatably attached to the balance support part of the main body or the magnetizer without contacting the surface of the round bar, and in a region where one of the two pairs of guide rollers on the left and right moves from a predetermined position on the end of the round bar to beyond the end, the metal plate with ball rollers contacts the surface of the round bar to activate a balance support mechanism that supports the balance of the main body, and a release mechanism releases the balance support mechanism in a region between the two pairs of guide rollers on the left and right and the predetermined positions on the end of the round bar.

5. A leakage flux inspection system for round bars comprising a rotating roller mechanism for rotating a round bar in a circumferential direction, a leakage flux inspection head for inspecting surface defects of the round bar, a inspection head operating mechanism for raising and lowering the leakage flux inspection head and moving it longitudinally along the surface of the round bar, and an inspection operation control device for controlling the inspection operation, characterized in that the leakage flux inspection system comprises a leakage flux inspection head according to any one of claims 1 to 4.

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